{"id":10293,"date":"2022-04-26T03:26:42","date_gmt":"2022-04-26T03:26:42","guid":{"rendered":"https:\/\/www.firstcomponents.com\/?p=10293"},"modified":"2023-01-17T06:22:02","modified_gmt":"2023-01-17T06:22:02","slug":"direct-mount-chainring-crank","status":"publish","type":"post","link":"https:\/\/www.firstcomponents.com\/de\/direct-mount-chainring-crank\/","title":{"rendered":"Direct Mount Chainring and Crank"},"content":{"rendered":"\n

A direct mount chainring is installed directly<\/em> onto an integrated crank which lacks the usual 4 or 5 arm spider. <\/p>\n\n\n\n

That gives you just a spindle, crank (arm) and mounted chainring.<\/p>\n\n\n\n

The advent of the direct mount chainring delivered the biggest advance in crank and chainring design since the introduction of integrated cranks.<\/p>\n\n\n\n

Keep reading to learn everything you need to know \u2014 including some pros and cons \u2014 about this most recent innovation in crank design.<\/p>\n\n\n\n

CONTENTS<\/strong><\/p>\n\n\n\n

Chainring Mounting Standards<\/a>
Advantages and Disadvantages of Direct Mount<\/a>
Direct Mount Chainring and Crank<\/a>
Direct Mount Chainring Installation<\/a>
Fitting a DM Chainring to a Crank<\/a>
Fitting the Crank into the BB<\/a><\/p>\n\n\n\n

Chainring Mounting Standards – From Direct Mount to . . . Direct Mount?<\/strong><\/h2>\n\n\n\n


In the beginning, the original Rover safety bike\u2019s crank used a front \u201csprocket\u201d; it was not yet called a chainring because it was one piece and not a ring of teeth bolted to the crank.<\/p>\n\n\n\n

This solid sprocket was part of the crank and functionally resembled what the industry today calls \u201cdirect mount\u201d.<\/p>\n\n\n\n

The chain connected the front sprocket to the rear sprocket; rear sprockets were \u2014 and remain \u2014 a ring of teeth bolted to a mount.<\/p>\n\n\n\n

A group of sprockets \u2014 the cassette \u2014 is mounted onto the cassette body<\/em> these days of course. The dramatic shift was to 5 arm spiders. Older cranks still have 5 arm spiders although 4 arm spiders are now the norm.<\/p>\n\n\n\n

The crucial specification is the bolt circle diameter (BCD), the measurement of the circumference of a circle connecting the center of the bolt holes on the chainring and spider arms.<\/p>\n\n\n\n

You can fit any chainring you want on any spider . . . as long as the BCD is the same for both parts.<\/p>\n\n\n\n

A direct mount crank gets rid of the spiders leaving you a crank (arm) and a spindle\u2014the chainring attaches to the inside of the crank using three bolts.<\/p>\n\n\n\n

Double direct mount chainrings<\/a><\/strong>\u00a0are also a thing although not so common.<\/p>\n\n\n\n

\"Embedded
Embedded from Shimano.com<\/figcaption><\/figure>\n\n\n\n

You can bolt another chainring to the direct mount chainring, creating a double chainring setup.<\/p>\n\n\n\n

Advantages and Disadvantages of Direct Mount Chainrings<\/strong><\/h2>\n\n\n\n


Lower weight and chain line optimization are two potential advantages, \u201cpotential\u201d since every rider prefers different setups, making generalizations moot. We\u2019ll make them all the same though . . . <\/p>\n\n\n\n

Should you make the change purely in order to \u201cupgrade\u201d from a standard crank to direct mount?<\/p>\n\n\n\n

Probably not (again, it\u2019s a personal thing). If you break something, then that\u2019s probably the best time to think about changing to a direct mount chainring and crank set.<\/p>\n\n\n\n

THE WEIGHT ADVANTAGE<\/strong><\/h3>\n\n\n\n


You reduce crank weight on a standard crank by removing the spider which consists of a base for the arms as well as the arms themselves.<\/p>\n\n\n\n

\"Spec:
Spec: narrow-wide, 30\/32\/34\/36\/38T, Shimano compatible<\/figcaption><\/figure>\n\n\n\n

Direct mount chainrings can be very finely machined even though they do contain more material than standard chainrings.<\/p>\n\n\n\n

\"Spec:
Spec: narrow-wide, 28\/30\/32\/34\/36T, Boost, Offset 3mm<\/figcaption><\/figure>\n\n\n\n

Nevertheless a finely machined mounted chainring on a finely machined crank makes for a significant weight reduction.<\/p>\n\n\n\n

\"Spec:
Spec: narrow-wide, 32\/34\/36T, Non-Boost, Offset 6mm<\/figcaption><\/figure>\n\n\n\n

Technically, a direct mount chainring incorporates the spider in the form of the arms connecting the direct mount teeth to the ring into which the teeth are machined.<\/p>\n\n\n\n

Still, that extra material is minimal in comparison with a crank and spider.<\/p>\n\n\n\n

THE CHAINLINE ADVANTAGE<\/strong><\/h3>\n\n\n\n


A 1x (narrow wide) chainring allows the precise adjustment of the chainline<\/a> since the single ring occupies the place of the middle chainring in the old 3x setup.<\/p>\n\n\n\n

A direct mount chainring gives you the option to run sub-28T chainrings which was not possible on a 104 BCD spider.<\/p>\n\n\n\n

DISADVANTAGES<\/strong><\/h3>\n\n\n\n


You have to remove your crank to remove and install a direct mount chainring which is not always necessarily with a standard chainring crank\u2014remove the bolts, slide the chainring off over the crank, slide the new one to the mounts, replace the bolts.<\/p>\n\n\n\n

Direct mount chainrings splines and grooves tend to be brand specific which limits you to the spec (size, offset, boost\/non-boost) they offer.<\/p>\n\n\n\n

Direct Mount Chainring . . . and Crank<\/strong><\/h2>\n\n\n\n


Calling this chainring\/crank design a direct mount chainring<\/em> focuses attention on the chainring at the expense of the crank.<\/p>\n\n\n\n

Fact is, a direct mount chainring fits to a redesigned crank that consists of just the crank arm fused to the spindle\u2014no more spider . . . which means no more worrying about the Bolt Circle Diameter (BCD).<\/p>\n\n\n\n

In the past you had to make sure the BCD of any chainring you were considering installing was the same size as the crank.<\/p>\n\n\n\n

Now you just need a chainring that slots onto the mount on the crank.<\/p>\n\n\n\n

That restricts you, of course, to chainrings that actually are compatible to the crank you\u2019re using.<\/p>\n\n\n\n

As long as that brand has the size you want (in the absence of cross-brand compatibility) you\u2019ll be in business.<\/p>\n\n\n\n

Direct Mount Chainring Installation<\/strong><\/h2>\n\n\n\n


We released our first direct mount crank<\/a> in March, 2022, although we\u2019ve had several direct mount chainring models<\/a> on the market for years.<\/p>\n\n\n\n

The direct mount installation procedure here details changing a standard integrated crank with a 4 arm spider to the FIRST Components direct mount crank.<\/p>\n\n\n\n

It\u2019s all in the video if you would prefer to watch.<\/p>\n\n\n\n